The effects of different wavelength UV photofunctionalization on micro-arc oxidized titanium

Nanofeatured surfaces in dental implants: contemporary insights and impending challenges

Dental implant therapy, established as standard-of-care nearly three decades ago with the advent of microrough titanium surfaces, revolutionized clinical outcomes through enhanced osseointegration. However, despite this pivotal advancement, challenges persist, including prolonged healing times, restricted clinical indications, plateauing success rates, and a notable incidence of peri-implantitis. This review explores the biological merits and constraints of microrough surfaces and evaluates the current landscape of nanofeatured dental implant surfaces, aiming to illuminate strategies for addressing existing impediments in implant therapy. Currently available nanofeatured dental implants incorporated nano-structures onto their predecessor microrough surfaces. While nanofeature integration into microrough surfaces demonstrates potential for enhancing early-stage osseointegration, it falls short of surpassing its predecessors in terms of osseointegration capacity. This discrepancy may be attributed, in part, to the inherent "dichotomy kinetics" of osteoblasts, wherein increased surface roughness by nanofeatures enhances osteoblast differentiation but concomitantly impedes cell attachment and proliferation. We also showcase a controllable, hybrid micro-nano titanium model surface and contrast it with commercially-available nanofeatured surfaces. Unlike the commercial nanofeatured surfaces, the controllable micro-nano hybrid surface exhibits superior potential for enhancing both cell differentiation and proliferation. Hence, present nanofeatured dental implants represent an evolutionary step from conventional microrough implants, yet they presently lack transformative capacity to surmount existing limitations. Further research and development endeavors are imperative to devise optimized surfaces rooted in fundamental science, thereby propelling technological progress in the field.

Comparison of the Photofunctionalization and Platelet-Rich Plasma in the Immediate Implants

Introduction

Many adjuvant methods have been researched to enhance the immediate implant success in the recent times. The study's goal was to compare the aesthetic and biological results of immediate dental implants in the aesthetic zone to standard tapered root form implants that had not undergone pre-treatment with platelet-rich plasma or photofunctionalization.

Materials and Methods

The study used a randomized controlled trial as its design. Ninety subjects were chosen at random and placed into three groups: a control group, a case group, and a group that needed replacement of their maxillary anterior teeth right away following extraction. The interventional groups received the "Platelet-Rich Plasma (PRP)" or "Photofunctionalization (PF)" group before the implant placement. After the delayed loading approach, the prosthesis was given after 6 months. At the second and fourth weeks, as well as 2, 4, 6, and 12 months (P 0.05), follow-up was conducted. The success and survival rate, aesthetic, and biological outcomes were assessed. One-way ANOVA was used to compare outcomes, and repeated-measures ANOVA was used to assess intragroup variations over baseline and follow-up.

Results

The distal, mesial, and mean marginal bone loss as well as the aesthetic scores for pink and white did not differ significantly between groups. The implant stability however was significantly higher in the PF and PRP groups as compared to the controls. A single implant failed in all the three groups. The success percentage was similar for all the groups.

Conclusion

The stability of immediate dental implants pre-treated with PRP or PF differed statistically significantly than the subjects in the control group, while other parameters remained the similar between the groups.

Nanoengineering and Surface Modifications of Dental Implants

Dental implants are one of the most important and successful advancements in modern dentistry. One aspect of dental implant design that influences the rate and degree of osseointegration is implant surface features. Nano-engineering techniques are anticipated to improve titanium dentistry implants' surface characteristics, which in turn promote peri-implant osteogenesis. In this paper, we review the recent advances in nanosurface engineering techniques for enhancing the bioactivity of dental implants.

Vacuum Ultraviolet (VUV) Light Photofunctionalization to Induce Human Oral Fibroblast Transmigration on Zirconia

Soft tissue adhesion and sealing around dental and maxillofacial implants, related prosthetic components, and crowns are a clinical imperative to prevent adverse outcomes of periodontitis and periimplantitis. Zirconia is often used to fabricate implant components and crowns. Here, we hypothesized that UV treatment of zirconia would induce unique behaviors in fibroblasts that favor the establishment of a soft tissue seal. Human oral fibroblasts were cultured on zirconia specimens to confluency before placing a second zirconia specimen (either untreated or treated with one minute of 172 nm vacuum UV (VUV) light) next to the first specimen separated by a gap of 150 µm. After seven days of culture, fibroblasts only transmigrated onto VUV-treated zirconia, forming a 2.36 mm volume zone and 5.30 mm leading edge. Cells migrating on VUV-treated zirconia were enlarged, with robust formation of multidirectional cytoplastic projections, even on day seven. Fibroblasts were also cultured on horizontally placed and 45° and 60° tilted zirconia specimens, with the latter configurations compromising initial attachment and proliferation. However, VUV treatment of zirconia mitigated the negative impact of tilting, with higher tilt angles increasing the difference in cellular behavior between control and VUV-treated specimens. Fibroblast size, perimeter, and diameter on day seven were greater than on day one exclusively on VUV-treated zirconia. VUV treatment reduced surface elemental carbon and induced superhydrophilicity, confirming the removal of the hydrocarbon pellicle. Similar effects of VUV treatment were observed on glazed zirconia specimens with silica surfaces. One-minute VUV photofunctionalization of zirconia and silica therefore promotes human oral fibroblast attachment and proliferation, especially under challenging culture conditions, and induces specimen-to-specimen transmigration and sustainable photofunctionalization for at least seven days.

Synergistic Enhancement of Protein Recruitment and Retention via Implant Surface Microtopography and Superhydrophilicity in a Computational Fluid Dynamics Model

The exact mechanisms by which implant surface properties govern osseointegration are incompletely understood. To gain insights into this process, we examined alterations in protein and blood recruitment around screw implants with different surface topographies and wettability using a computational fluid dynamics (CFD) model. Compared with a smooth surface, a microrough implant surface reduced protein infiltration from the outer zone to the implant thread and interface zones by over two-fold. However, the microrough implant surface slowed blood flow in the interface zone by four-fold. As a result, compared with the smooth surface, the microrough surface doubled the protein recruitment/retention index, defined as the mass of proteins present in the area per unit time. Converting implant surfaces from hydrophobic to superhydrophilic increased the mass of protein infiltration 2-3 times and slowed down blood flow by up to two-fold in the implant vicinity for both smooth and microrough surfaces. The protein recruitment/retention index was highest at the implant interface when the implant surface was superhydrophilic and microrough. Thus, this study demonstrates distinct control of the mass and speed of protein and blood flow through implant surface topography, wettability, and their combination, significantly altering the efficiency of protein recruitment. Although microrough surfaces showed both positive and negative impacts on protein recruitment over smooth surfaces, superhydrophilicity was consistently positive regardless of surface topography.

Evaluation of UV photofunctionalization effect on ultrastructural properties of SLA titanium disks: An in vitro study

Background

The success rate of dental implants diminishes over time; the lack of osseointegration and infection are the major causes of most implant failures. One of the effective methods to improve the surface properties is to irradiate ultraviolet (UV) light. This study investigated the effect of UV photofunctionalization on the ultrasuperficial properties of sandblasted, large-grit, acid-etched (SLA) titanium discs.

Methods

In this in vitro study, 24 sandblasted and acid-etched titanium discs, with a lifespan of more than four weeks, were categorized into three groups (n=8): control, ultraviolet C (UVC), and ultraviolet B (UVB). Then, they were exposed to a UV light source for 48 hours at a 1-cm distance. In addition to measuring the contact angle between the liquid and the disc surface in each of the three groups, the atomic concentrations of carbon, oxygen, and nitrogen atoms were measured at three different sites on each disc. One-way ANOVA and post hoc Tukey tests were used to analyze data.

Results

The mean concentration of carbon atoms significantly differed in the control, UVC, and UVB groups (P<0.001). The mean concentrations of nitrogen atoms differed significantly between the three groups (P<0.001). However, the mean concentrations of oxygen atoms were not significantly different between the three groups. In examining the contact angle, wettability was higher in the UVC group than in the UVB group and higher in the UBV group than in the control group.

Conclusion

Photofunctionalization with UV light significantly decreased carbon and nitrogen concentrations on the surface of titanium implants, indicating that the implant's superficial hydrocarbons were eliminated. It was observed that UVC photofunctionalization was more effective than UVB photofunctionalization in reducing superficial contamination and improving wettability.

Assessment of the Effect of Phototherapy and PRP on the Immediate Implants: An Original Research

Immediate implants have been gaining popularity in recent times. There are many adjuvant techniques that are followed before implant placement, which have recently shown hopeful results. For this reason, the current comparative study analyzes the effectiveness of platelet-rich plasma (PRP) and photofunctionalization (PF) at a tertiary care dental hospital. In the current clinical trial, 30 subjects were grouped equally to receive immediate dental implants, with one group in which pretreatment of the extraction site was done with the auto-PRP and PF, while the control group received no pretreatment. For 12 months after the placement of the implant, the subjects were observed for alterations in the parameters. The variables analyzed were survival, esthetics, biological integration, and finally the success of the implants in each group. Values were noted and compared using the appropriate statistical tools, while keeping the level of significance at P < 0.05. For the variables of esthetics and survival, no substantial differences were observed in the PRP and PF groups. There was no difference between these experimental groups and the control group. However, there were significant differences for the biological variable as there was more marginal bone loss in the experimental groups. On the whole, the success was greater for the experimental groups than the control group, though not significant. The pretreatment protocols using PRP and PF have shown to improve some characteristics of the immediate implants in the anterior regions. However, further studies are suggested.

In-Vitro Evaluation of Photofunctionalized Implant Surfaces in a High-Glucose Microenvironment Simulating Diabetics

The present study aimed to assess the efficacy of photofunctionalization on commercially available dental implant surfaces in a high-glucose environment. Discs of three commercially available implant surfaces were selected with various nano- and microstructural alterations (Group 1—laser-etched implant surface, Group 2—titanium–zirconium alloy surface, Group 3—air-abraded, large grit, acid-etched surface). They were subjected to photo-functionalization through UV irradiation for 60 and 90 min. X-ray photoelectron spectroscopy (XPS) was used to analyze the implant surface chemical composition before and after photo-functionalization. The growth and bioactivity of MG63 osteoblasts in the presence of photofunctionalized discs was assessed in cell culture medium containing elevated glucose concentration. The normal osteoblast morphology and spreading behavior were assessed under fluorescence and phase-contrast microscope. MTT (3-(4,5 Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and alizarin red assay were performed to assess the osteoblastic cell viability and mineralization efficiency. Following photofunctionalization, all three implant groups exhibited a reduced carbon content, conversion of Ti4+ to Ti3+, increased osteoblastic adhesion, viability, and increased mineralization. The best osteoblastic adhesion in the medium with increased glucose was seen in Group 3. Photofunctionalization altered the implant surface chemistry by reducing the surface carbon content, probably rendering the surfaces more hydrophilic and conducive for osteoblastic adherence and subsequent mineralization in high-glucose environment.

A Novel High-Energy Vacuum Ultraviolet Light Photofunctionalization Approach for Decomposing Organic Molecules around Titanium

Titanium undergoes biological aging, represented by increased hydrophobicity and surface accumulation of organic molecules over time, which compromises the osseointegration of dental and orthopedic implants. Here, we evaluated the efficacy of a novel UV light source, 172 nm wavelength vacuum UV (VUV), in decomposing organic molecules around titanium. Methylene blue solution used as a model organic molecule placed in a quartz ampoule with and without titanium specimens was treated with four different UV light sources: (i) ultraviolet C (UVC), (ii) high-energy UVC (HUVC), (iii) proprietary UV (PUV), and (iv) VUV. After one minute of treatment, VUV decomposed over 90% of methylene blue, while there was 3-, 3-, and 8-fold more methylene blue after the HUVC, PUV, and UVC treatments, respectively. In dose-dependency experiments, maximal methylene blue decomposition occurred after one minute of VUV treatment and after 20-30 min of UVC treatment. Rapid and effective VUV-mediated organic decomposition was not influenced by the surface topography of titanium or its alloy and even occurred in the absence of titanium, indicating only a minimal photocatalytic contribution of titanium dioxide to organic decomposition. VUV-mediated but not other light source-mediated methylene blue decomposition was proportional to its concentration. Plastic tubes significantly reduced methylene blue decomposition for all light sources. These results suggest that VUV, in synergy with quartz ampoules, mediates rapid and effective organic decomposition compared with other UV sources. This proof-of-concept study paves the way for rapid and effective VUV-powered photofunctionalization of titanium to overcome biological aging.

Decomposing Organic Molecules on Titanium with Vacuum Ultraviolet Light for Effective and Rapid Photofunctionalization

Ultraviolet (UV) photofunctionalization counteracts the biological aging of titanium to increase the bioactivity and osseointegration of titanium implants. However, UV photofunctionalization currently requires long treatment times of between 12 min and 48 h, precluding routine clinical use. Here, we tested the ability of a novel, xenon excimer lamp emitting 172 nm vacuum UV (VUV) to decompose organic molecules coated on titanium as a surrogate of photofunctionalization. Methylene blue as a model organic molecule was coated on grade 4 commercially pure titanium and treated with four UV light sources: (i) ultraviolet C (UVC), (ii) high-energy UVC (HUVC), (iii) proprietary UV (PUV), and (iv) VUV. After one minute of treatment, VUV decomposed 57% of methylene blue compared with 2%, 36%, and 42% for UVC, HUVC, and PUV, respectively. UV dose-dependency testing revealed maximal methylene blue decomposition with VUV within one minute. Equivalent decomposition was observed on grade 5 titanium alloy specimens, and placing titanium specimens in quartz ampoules did not compromise efficacy. Methylene blue was decomposed even on polymethyl methacrylate acrylic specimens at 20-25% lower efficiency than on titanium specimens, indicating a relatively small contribution of titanium dioxide-mediated photocatalytic decomposition to the total decomposition. Load-testing revealed that VUV maintained high efficacy of methylene blue decomposition regardless of the coating density, whereas other UV light sources showed low efficacy with thin coatings and plateauing efficacy with thicker coatings. This study provides foundational data on rapid and efficient VUV-mediated organic decomposition on titanium. In synergy with quartz ampoules used as containers, VUV has the potential to overcome current technical challenges hampering the clinical application of UV photofunctionalization.

Clinical Effects of Photofunctionalization on Implant Stability and Marginal Bone Loss: Systematic Review and Meta-Analysis

BACKGROUND

Several clinical trials have recently been conducted to elucidate the effectiveness of photofunctionalization. The aim of this review was to systematically analyze the clinical effects of photofunctionalization on implant stability and marginal bone loss (MBL).

METHODS

An electronic search in four databases and a manual search were conducted in September 2022. Randomized controlled trials (RCTs), clinical controlled trials (CCTs), and cohort and case-control studies evaluating the effects of photofunctionalization on implant stability or marginal bone loss (MBL) in humans were included. The methodological quality assessment using RoB 2.0 and the ROBINS-I tool was performed based on different study designs.

RESULTS

Seven studies were included for a qualitative analysis, and five of them were chosen for a meta-analysis. The meta-analysis revealed that photofunctionalization significantly improved the stability of the implant 2 months after implantation (p = 0.04; MD = 3.48; 95% CI = -0.23 to 6.73) and increased the osseointegration speed index (OSI) (p = 0.007; MD = 2.13; 95% CI = 0.57 to 3.68). However, no significant improvements of implant stability were observed 2 weeks (p = 0.62), 4 weeks (p = 0.31), nor 4 months (p = 0.24) after implantation. The evaluation presented no significant reductions in MBL.

CONCLUSIONS

Based on the positive effect of photofunctionalization on the rate of establishing implant stability, photofunctionalization may provide an effective and practical strategy to achieve faster osseointegration and reduce the overall healing time. Photofunctionalization appears to improve the implant stability. However, the clinical effect of photofunctionalization on MBL remains unclear due to the shortage of available studies.

Plasma of Argon Treatment of the Implant Surface, Systematic Review of In Vitro Studies

This paper aims to review the evidence of the cellular activity on titanium samples exposed to Plasma of Argon (PoA) treatment. A systematic review was carried out based on the PRISMA statement by searching the Cochrane Library, PubMed, Web of Science, EMBASE and Scopus, up to October 2020. Papers were selected according to PICOS format that is: Population (P): osteoblasts, fibroblasts, gingival cells; Intervention (I): PoA disinfection treatment; Comparison (C): untreated controls; Outcome (O): cell culture; Setting (S): in vitro assays. The quality assessment was performed according to the CRIS Guidelines (Checklist for Reporting In vitro Studies). A total of 661 articles were found, of which 16 were included. The quality assessment revealed an overall poor quality of the studies analyzed. In vitro studies on the potential of PoA showed a potential effect in promoting higher cell adhesion and protein adsorption in the earliest times (hours). This outcome was not so evident when later stages of cell growth on the surfaces were tested and compared to the control groups. Only one study was conducted in vivo on a human sample regarding abutment cleaning. No meta-analysis was conducted because of the variety of experimental settings, mixed methods and different cell lines studied. PoA seems to be effective in promoting cell adhesion and protein adsorption. The duration of this effect remains unclear. Further evidence is required to demonstrate the long-term efficacy of the treatment and to support the use of PoA treatment in clinical practice.

Bioactive Coatings on Titanium: A Review on Hydroxylation, Self-Assembled Monolayers (SAMs) and Surface Modification Strategies

Titanium (Ti) and its alloys have been demonstrated over the last decades to play an important role as inert materials in the field of orthopedic and dental implants. Nevertheless, with the widespread use of Ti, implant-associated rejection issues have arisen. To overcome these problems, antibacterial properties, fast and adequate osseointegration and long-term stability are essential features. Indeed, surface modification is currently presented as a versatile strategy for developing Ti coatings with all these challenging requirements and achieve a successful performance of the implant. Numerous approaches have been investigated to obtain stable and well-organized Ti coatings that promote the tailoring of surface chemical functionalization regardless of the geometry and shape of the implant. However, among all the approaches available in the literature to functionalize the Ti surface, a promising strategy is the combination of surface pre-activation treatments typically followed by the development of intermediate anchoring layers (self-assembled monolayers, SAMs) that serve as the supporting linkage of a final active layer. Therefore, this paper aims to review the latest approaches in the biomedical area to obtain bioactive coatings onto Ti surfaces with a special focus on (i) the most employed methods for Ti surface hydroxylation, (ii) SAMs-mediated active coatings development, and (iii) the latest advances in active agent immobilization and polymeric coatings for controlled release on Ti surfaces.

Biological and esthetic outcome of immediate dental implant with the adjunct pretreatment of immediate implants with platelet-rich plasma or photofunctionalization: A randomized controlled trial

Aim

The purpose of the study was to assess biological and esthetic outcomes of immediate dental implant in esthetic zone with the adjunct pretreatment of immediate implants with photofunctionalization or platelet-rich plasma in comparison to standard tapered root form implant without pretreatment.

Settings and Design

Patients visiting department of Prosthodontics of a tertiary care health Institution. Design of the study was randomized controlled trial.

Materials and Methods

Ninety subjects who required replacement of maxillary anterior teeth immediately after extraction were selected and randomly divided into three groups: control group and two case groups. Two case groups were treated with immediate implants with pretreatment with Photofunctionalization (PF group) or platelet-rich plasma (PRP group). Delayed loading protocol was followed with prosthesis given after 6 months. Follow-up was performed at 2nd and 4th weeks and 2, 4, 6, and 12 months (P < 0.05). Biological outcomes (mean marginal bone loss, implant stability), esthetic outcome (pink esthetic score and white esthetic score), and success and survival rate were evaluated.

Statistical Analysis Used

Outcomes were compared using one-way ANOVA, while intragroup changes with baseline and follow up were assesed using repeated-measures ANOVA. Statistical analyses were performed using Statistical Package for Social Sciences version 25.0 (SPSS Inc., Chicago, IL, USA). The level of significance was set at <.05.

Results

Mean marginal bone loss was not significantly different in PF group and PRP group than the control group. PF group and PRP group showed significantly greater implant stability as compared to the control group. Pink and white esthetic scores were not significantly different among groups.

Conclusion

Pretreatment of commercial dental implants with PF or PRP exhibited a statistically significant difference in implant stability but not with other outcomes.

The Cleaning Effect of the Photocatalysis of TiO2-B＠anatase Nanowires on Biological Activity on a Titanium Surface

Background

Improvements in the early osseointegration of titanium implants require investigations on the bone-implant interface, which is a critical and complex challenge. The surface cleanliness of titanium implants plays an important role at this interface. However, the implant surface would inevitably absorb contamination such as organic hydrocarbons, which is not conductive to the establishment of early osseointegration. Herein, an optimized approach for removing contamination from titanium surfaces was studied.

Methods

The TiO₂-B＠anatase NWs (nanowires) were prepared on titanium substrates through a hydrothermal process. A methylene blue degradation experiment was performed to assess the photodegradation activity. The cleaning effect of the photocatalysis of TiO₂-B＠anatase NWs on a titanium surface and the cellular early response was determined by analyzing cell morphology, attachment, proliferation and differentiation.

Results

The results indicated that the photocatalysis of TiO₂-B＠anatase NWs could effectively remove hydrocarbons on titanium surfaces without sacrificing the favourable titanium surface morphology. The methylene blue degradation experiment revealed that the photocatalysis of TiO₂-B＠anatase NWs had powerful degradation activity, which is attributed to the presence of strong oxidants such as ^·OH. In addition, compared to the merely ultraviolet-treated titanium surfaces, the titanium surfaces treated after the NWs photocatalytic cleaning process markedly enhanced cellular early response.

Conclusion

The photocatalysis of TiO₂-B＠anatase NWs for the removal of contamination from titanium surfaces has the potential to enable the rapid and complete establishment of early osseointegration.

Improvement in the chemical structure and biological activity of surface titanium after exposure to UVC light

Ultraviolet (UV) irradiation has been proposed as a method to reverse the aging process of titanium. However, the intensity, exposure time and wavelength that provide the best results have not yet been determined. The objective of this study was to evaluate the effects of photocatalysis by ultraviolet C light on the time-dependent aging of titanium and to analyze the irradiated titanium for changes in structure and in vitro biological activity, with regard to different exposure times. A titanium photofunctionalization device was developed with characteristics different from those on the market. The sample was composed of titanium disks irradiated for different times of exposure to ultraviolet C light (0, 15, 30 and 60 min). The disks were tested for surface wettability (water contact angle), topography (scanning electron microscopy-SEM) and chemical composition (X-ray photoelectron spectroscopy), and effects on cell adhesion (cell culture and SEM) and cell viability by sulforhodamine B (SRB). Ultraviolet C treatment caused changes in titanium surface characteristics, such as increased wettability and removal of hydrocarbons from the surface after 15 min of exposure in the chamber developed. The biological characteristics of the material also appear to have changed, with improved cell adhesion and viability. Photofunctionalization of titanium proved to be effective for the treatment of aged surfaces, with significant modifications in the surface chemical structure and biological activity of the material.

Ultraviolet Radiant Energy-Dependent Functionalization Regulates Cellular Behavior on Titanium Dioxide Nanodots

Titanium dioxide (TiO₂) photofunctionalization has been demonstrated as an effective surface modification method for the osseointegration of implants. However, the insufficient understanding of the mechanism underlying photofunctionalization limits its clinical applications. Here, we report an ultraviolet (UV) radiant energy-dependent functionalization on TiO₂ nanodots (TN) surfaces. We found the cell adhesion, proliferation, and osteogenic differentiation gradually increased with the accumulation of UV radiant energy (URE). The optimal functionalizing treatment energy was found to be 2000 mJ/cm², which could regulate cell-specific behaviors on TN surfaces. The enhanced cell behaviors were regulated by the adsorption and functional site exposure of the extracellular matrix (ECM) proteins, which were the result of the surface physicochemical changes induced by the URE. The correlation between the URE and the reconstruction of surface hydroxyl groups was considered as an alternative mechanism of this energy-dependent functionalization. We also demonstrated the synergistic effects of FAK-RHOA and ERK1/2 signaling pathways on mediating the URE-dependent cell behaviors. Overall, this study provides a novel insight into the mechanisms of photofunctionalization, guiding the design of implants and the clinical practice of photofunctionalization.

Photofunctionalization as a suitable approach to improve the osseointegration of implants in animal models-A systematic review and meta-analysis

OBJECTIVES

To determine whether photofunctionalization influences dental implant osseointegration.

MATERIAL AND METHODS

Data on osseointegration rates were extracted from 8 databases, based on bone-to-implant contact (BIC) and pushout tests. Internal validity was accessed through the SYRCLE risk of bias tool for animal experimental studies. Meta-analyses were performed for investigation of the influence of photofunctionalization on implant osseointegration, with a random effect and a confidence interval of 95%. The certainty of evidence was accessed through the GRADE approach.

RESULTS

Thirty-four records were identified, and 10 were included in the meta-analysis. Photofunctionalized implants showed higher mean values for BIC in rabbits (MD 6.92 [1.01, 12.82], p = .02), dogs (MD 23.70 [10.23, 37.16], p = .001), rats (MD 20.93 [12.91, 28.95], p < .0001), and in the pooled BIC analyses (MD 14.23 [7.80, 20.66], p < .0001) compared to those in control implants in the overall assay. Conversely, at late healing periods, the pooled BIC meta-analyses showed no statistically significant differences (p > .05) for photofunctionalized and control implants at 12 weeks of follow-up. For pushout analysis, photofunctionalized implants presented greater bone strength integration (MD 19.92 [13.88, 25.96], p < .0001) compared to that of control implants. The heterogeneity between studies ranged from "not important" to "moderate" for rabbits I²  = 24%, dogs I²  = 0%, rats I²  = 0%, and pooled BIC (I²  = 49%), while considerable heterogeneity was observed for pushouts (I²  = 90%).

CONCLUSION

Photofunctionalization improves osseointegration in the initial healing period of implants, as summarized from available data from rabbit, dog, and rat in vivo models.

Effects of Ultraviolet Photoactivation on Osseointegration of Commercial Pure Titanium Dental Implant After 8 Weeks in a Rabbit Model

This study investigated whether a 6-Watt ultraviolet C-lamp was capable of producing photofunctionalization on commercial implants during a medium observation term of 8 weeks. A total of 20 implants were inserted in 5 New Zealand rabbits, with each animal receiving 2 implants per tibia (one photofunctionalized and one untreated), according to a previously established randomization sequence. All implants were inserted by a single surgeon following the manufacturer's instructions. Histological analysis was performed by an evaluator who was blinded to the treatment condition. After 8 weeks of healing, the 2 groups showed no statistically significant differences in terms of bone-to-implant contact. Compared to control implants, the photofunctionalized implants showed improved wettability and more homogenous results. Within the limits of the present study, the use of this 6-W ultraviolet C-lamp, for an irradiation time of 15 minutes at a distance of 15 cm, did not improve the percentages of bone-to-implant contact in rabbits at an osseointegration time of 8 weeks.

Computational Fluid Simulation of Fibrinogen around Dental Implant Surfaces

Ultraviolet treatment of titanium implants makes their surfaces hydrophilic and enhances osseointegration. However, the mechanism is not fully understood. This study hypothesizes that the recruitment of fibrinogen, a critical molecule for blood clot formation and wound healing, is influenced by the degrees of hydrophilicity/hydrophobicity of the implant surfaces. Computational fluid dynamics (CFD) implant models were created for fluid flow simulation. The hydrophilicity level was expressed by the contact angle between the implant surface and blood plasma, ranging from 5° (superhydrophilic), 30° (hydrophilic) to 50° and 70° (hydrophobic), and 100° (hydrorepellent). The mass of fibrinogen flowing into the implant interfacial zone (fibrinogen infiltration) increased in a time dependent manner, with a steeper slope for surfaces with greater hydrophilicity. The mass of blood plasma absorbed into the interfacial zone (blood plasma infiltration) was also promoted by the hydrophilic surfaces but it was rapid and non-time-dependent. There was no linear correlation between the fibrinogen infiltration rate and the blood plasma infiltration rate. These results suggest that hydrophilic implant surfaces promote both fibrinogen and blood plasma infiltration to their interface. However, the infiltration of the two components were not proportional, implying a selectively enhanced recruitment of fibrinogen by hydrophilic implant surfaces.

Ultraviolet A and Ultraviolet C Light-Induced Reduction of Surface Hydrocarbons on Titanium Implants

Objective The carbon, titanium, and oxygen levels on titanium implant surfaces with or without ultraviolet (UV) pretreatment were evaluated at different wavelengths through X-ray photoelectron spectroscopy (XPS).

Materials and Methods This interventional experimental study was conducted on nine Dio UFII implants with hybrid sandblasted and acid-etched (SLA) surface treatments, divided equally into three groups. Control group A samples were not given UV irradiation, while groups B and C samples were given UVA (382 nm, 25 mWcm ² ) and UVC (260 nm, 15 mWcm ² ) irradiation, respectively. The atomic ratio of carbon, titanium, and oxygen was compared through XPS.

Results Mean carbon-to-titanium ratio and C1 peaks considerably increased in Group A compared to those in experimental Groups B and C. The intensity of Ti2p and O1s peaks was more pronounced for group C compared to that for groups A and B.

Conclusions Although the decrease in surface hydrocarbons was the same in both UV-treated groups, the peak intensity of oxygen increased in the UVC-treated group. Thus, it can be concluded that compared with UVA irradiation, UVC irradiation has the potential to induce more hydrophilicity on SLA-coated implants.

Ultraviolet Functionalization Improved Bone Integration on Titanium Surfaces by Fluorescent Analysis in Rabbit Calvarium

This study evaluated the effect of ultraviolet functionalization (UV) on bone integration ability in rabbit model, using epifluorescence microscopy. Each of 12 rabbits (n = 6) received randomly four titanium domes prepared with or without ultraviolet for 48 hours (UVC, λ = 250 ± 20 nm; Philips, Tokyo, Japan): (1) turned surface (T), (2) turned surface with UV (T-UV), (3) sandblasted (120 μm aluminum oxide) and etched by 18% hydrochloric acid and 49% sulphuric acid at 60°C for 30 min (SLA) and (4) SLA surface with UV (SLA-UV). Fluorochrome bone labels were marked by oxytetracycline at 25 mg/kg on 13th days and 14th days and calcein at 5 mg/kg on 3th days and 4th days before euthanization. The study samples were sacrified at 2 weeks and 4 weeks. The undecalcified specimens were prepared. The newly formed total bone of cross-sectional area (TB, %), the mineralized trabecular bone of cross-sectional area (MB, %), and the new bone and dome contact (BDC, %) were measured and analyzed by fluorescence microscope and Image Pro Express 6.0. The data of MB and TB showed new bone regeneration was increased in all groups, but no signs of difference were found. However, the means BDC of UV treatment on turned surface at 4 weeks, the UV treated on SLA surface at 2 weeks and 4 weeks were statistically significantly higher than the control group (P &lt; .05). Within the limitations of the study, it can be concluded that ultraviolet functionalization on the titanium surface could enhance the new bone tissues and titanium surface integration.

The impact of photofunctionalized gold nanoparticles on osseointegration

OBJECTIVES

The aims of this study were to create a new surface topography using simulated body fluids (SBF) and Gold Nanoparticles (GNPs) and then to assess the influence of UV Photofunctionalization (PhF) on the osteogenic capacity of these surfaces.

MATERIALS AND METHODS

Titanium plates were divided into six groups All were acid etched with 67% Sulfuric acid, 4 were immersed in SBF and 2 of these were treated with 10 nm GNPs. Half of the TiO2 plates were photofunctionalized to be compared with the non-PhF ones. Rat's bone marrow stem cells were seeded into the plates and then CCK8 assay, cell viability assay, immunofluorescence, and Scanning electron microscopy (SEM) were done after 24 hours. Gene expression analysis was done using real time quantitative PCR (qPCR) one week later to check for the mRNA expression of Collagen-1, Osteopontin and Osteocalcin. Alkaline phosphatase (ALP) activity was assessed after 2 weeks of cell seeding.

RESULTS

Our new topography has shown remarkable osteogenic potential. The new surface was the most biocompatible, and the 10 nm GNPs did not show any cytotoxicity. There was a significant increase in bioactivity, enhanced gene expressions and ALP activity.

CONCLUSIONS

GNPs enhances osteogenic differentiation of stem cells and Photofunctionalizing GNPs highly increases this. We have further created a novel highly efficient topography which highly enhances the speed and extent of osseointegration. This may have great potential for improving treatment outcomes for implant, maxillofacial as well as orthopedic patients.

Photofunctionalization of anodized titanium surfaces using UVA or UVC light and its effects against Streptococcus sanguinis

UV light preirradiation of anodized titanium oxide layers has recently been shown to produce a photocatalytic effect that may reduce early bacterial attachment on titanium surfaces. Streptococcus species have been identified as primary early colonizers and contribute to early biofilm formation on dental implant surfaces. Anodized layers with primarily amorphous, primarily anatase, primarily rutile, and mixtures of anatase and rutile phase oxides were preirradiated with UVA or UVC light for 10 min. Nanoscale surface roughness and pre- and post-UV-irradiated wettability were measured for each anodization group. Sample groups were subjected to streptococcus sanguinis for a period of 24 h. Bacterial attachment and killing efficacy were measured and compared to the corresponding non-UV control groups. UVA treatments showed trends of at least a 20% reduction in bacterial attachment regardless of the crystallinity, or combination of oxide phases present. Anodized layers consisting of primarily anatase phase on the outermost surface were shown to have a killing efficacy of at least 50% after preirradiation with UVA light. Anodized layers containing disperse mixtures of anatase and rutile phases at the outermost surface showed at least a 50% killing efficacy after pre-irradiation with either UVA or UVC light. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2284-2294, 2018.

Photofunctionalization and non-thermal plasma activation of titanium surfaces

OBJECTIVE

The aim of this study was to compare UV light and non-thermal plasma (NTP) treatment regarding the improvement of physical material characteristics and cell reaction on titanium surfaces in vitro after short-term functionalization.

MATERIALS AND METHODS

Moderately rough (Ra 1.8-2.0 μm) sandblasted and acid-etched titanium disks were treated by UV light (0.05 mW/cm² at λ = 360 nm and 2 mW/cm² at λ = 250 nm) or by NTP (24 W, -0.5 mbar) of argon or oxygen for 12 min each. Surface structure was investigated by scanning electron microscopy, confocal microscopy and X-ray photoelectron spectroscopy (XPS). Hydrophilicity was assessed by dynamic contact angle measurement. Cell attachment, viability, cell proliferation and cytotoxicity were assessed in vitro using murine osteoblast-like cells.

RESULTS

UV irradiation or NTP treatment of titanium surfaces did not alter the surface structure. XPS analysis revealed a significantly increased oxidation of the surface and a decrease of carbon after the use of either method. NTP and UV light led to a significant better cell attachment of murine osteoblasts; significantly more osteoblasts grew on the treated surfaces at each time point (p < 0.001).

CONCLUSIONS

UV light as well as NTP modified the surface of titanium and significantly improved the conditions for murine osteoblast cells in vitro. However, results indicate a slight advantage for NTP of argon and oxygen in a short time interval of surface functionalization compared to UV.

CLINICAL RELEVANCE

UV light and NTP are able to improve surface conditions of dental implants made of titanium.

Impact of Dental Implant Surface Modifications on Osseointegration

Objective. The aim of this paper is to review different surface modifications of dental implants and their effect on osseointegration. Common marketed as well as experimental surface modifications are discussed. Discussion. The major challenge for contemporary dental implantologists is to provide oral rehabilitation to patients with healthy bone conditions asking for rapid loading protocols or to patients with quantitatively or qualitatively compromised bone. These charging conditions require advances in implant surface design. The elucidation of bone healing physiology has driven investigators to engineer implant surfaces that closely mimic natural bone characteristics. This paper provides a comprehensive overview of surface modifications that beneficially alter the topography, hydrophilicity, and outer coating of dental implants in order to enhance osseointegration in healthy as well as in compromised bone. In the first part, this paper discusses dental implants that have been successfully used for a number of years focusing on sandblasting, acid-etching, and hydrophilic surface textures. Hereafter, new techniques like Discrete Crystalline Deposition, laser ablation, and surface coatings with proteins, drugs, or growth factors are presented. Conclusion. Major advancements have been made in developing novel surfaces of dental implants. These innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions.

Photofunctionalization of Dental Implants

After dental implants are manufactured there can be a loss of biological activity that may be reactivated by exposure to ultraviolet (UV) radiation, that is, photofunctionalization. The titanium surface is energy conditioned by UV radiation. This imparts a slight positive surface energy and hydrophilicity to the titanium dental implant surface. This conditioning renews biological activity lost after a shelf life of as little as 2 weeks. The UV radiation has chemical and biological effects on the osseous-implant interface. Photofunctionization for as little as 15 minutes accelerates healing and increases bone to implant contact. The most effective time exposure and UV wave length are in need of identification to produce a surface most conducive for osseointegration.

A Strontium-Modified Titanium Surface Produced by a New Method and Its Biocompatibility In Vitro

OBJECTIVE

To present a new and effective method of producing titanium surfaces modified with strontium and to investigate the surface characteristics and in vitro biocompatibility of titanium (Ti) surfaces modified with strontium (Sr) for bone implant applications.

MATERIALS AND METHODS

Sr-modified Ti surfaces were produced by sequential treatments with NaOH, strontium acetate, heat and water. The surface characteristics and the concentration of the Sr ions released from the samples were examined. Cell adhesion, morphology and growth were investigated using osteoblasts isolated from the calvaria of neonatal Sprague-Dawley rats. Expression of osteogenesis-related genes and proteins was examined to assess the effect of the Sr-modified Ti surfaces on osteoblasts.

RESULTS

The modified titanium surface had a mesh structure with significantly greater porosity, and approximately5.37±0.35at.% of Sr was incorporated into the surface. The hydrophilicity was enhanced by the incorporation of Sr ions and water treatment. The average amounts of Sr released from the Sr-modified plates subjected to water treatment were slight higher than the plates without water treatment. Sr promoted cellular adhesion, spreading and growth compared with untreated Ti surfaces. The Sr-modified Ti plates also promoted expression of osteogenesis-related genes,and expression of OPN and COL-І by osteoblasts. Ti plates heat treated at 700°C showed increased bioactivity in comparison with those treated at 600°C. Water treatment upregulated the expression of osteogenesis-related genes.

CONCLUSIONS

These results show that Sr-modification of Ti surfaces may improve bioactivity in vitro. Water treatment has enhanced the response of osteoblasts. The Sr-modified Ti heat-treated at 700°C exhibited better bioactivity compared with that heated at 600°C.

Biological Effect of Ultraviolet Photocatalysis on Nanoscale Titanium with a Focus on Physicochemical Mechanism

Physicochemical properties, regulated by various surface modifications, influence the biological performance of materials. The interaction between surface charge and biomolecules is key to understanding the mechanism of surface-tissue integration. The objective of this study was to evaluate the biological response to a nanoscale titanium surface after ultraviolet (UVC, λ = 250 ± 20 nm) irradiation and to analyze the effects via a physicochemical mechanism. The surface characteristics were evaluated by field-emission scanning electron microscopy, X-ray photoelectron spectroscopy, surface profilometry, and contact angle assay. In addition, we applied the zeta-potential, a direct method to measure the electrostatic charge on UV-treated and UV-untreated titanium nanotube surfaces. The effect of the Ti surface after UV treatment on the biological process was determined by analyzing bovine serum albumin (BSA) adsorption and osteoblast-like MG-63 early adhesion, morphology, cytoskeletal arrangement, proliferation, and focal adhesion. Compared to an anodized titanium nanotube coating, UV irradiation altered the contact angles on the control surface from 51.5° to 6.2° without changing the surface topography or roughness. Furthermore, titanium nanotubes after UV treatment showed a significant reduction in the content of acidic hydroxyl groups and held less negative charge than the anodized coating. With regard to the biological response, along with an enhanced capability to adsorb BSA, osteoblasts exhibited higher colonization and viability on the UV-treated material. The results suggest that UV treatment enhances the biocompatibility by reducing the electrostatic repulsion between biomaterials and biomolecules.

Surface properties of nanocrystalline TiO2 coatings in relation to the in vitro plasma protein adsorption

This study reports on the selective adsorption of whole plasma proteins on hydrothermally (HT) grown TiO2-anatase coatings and its dependence on the three main surface properties: surface charge, wettability and roughness. The influence of the photo-activation of TiO2 by UV irradiation was also evaluated. Even though the protein adhesion onto Ti-based substrates was only moderate, better adsorption of any protein (at pH = 7.4) occurred for the most negatively charged and hydrophobic substrate (Ti non-treated) and for the most nanorough and hydrophilic surface (HT Ti3), indicating that the mutual action of the surface characteristics is responsible for the attraction and adhesion of the proteins. The HT coatings showed a higher adsorption of certain proteins (albumin 'passivation' layer, apolipoproteins, vitamin D-binding protein, ceruloplasmin, α-2-HS-glycoprotein) and higher ratios of albumin to fibrinogen and albumin to immunoglobulin γ-chains. The UV pre-irradiation affected the surface properties and strongly reduced the adsorption of the proteins. These results provide in-depth knowledge about the characterization of nanocrystalline TiO2 coatings for body implants and provide a basis for future studies on the hemocompatibility and biocompatibility of such surfaces.

Enhanced osteogenesis on titanium implants by UVB photofunctionalization of hydrothermally grown TiO₂ coatings

Even though Ti-based implants are the most used materials for hard tissue replacement, they may present lack of osseointegration on the long term, due to their inertness. Hydrothermal treatment (HT) is a useful technique for the synthesis of firmly attached, highly crystalline coatings made of anatase titanium dioxide (TiO2), providing favorable nanoroughness and higher exposed surface area, as well as greater hydrophilicity, compared to the native amorphous oxide on pristine titanium. The hydrophilicity drops even more by photofunctionalization of the nanostructured TiO2-anatase coatings under UV light. Human mesenchymal stem cells exhibited a good response to the combination of the positive surface characteristics, especially in respect to the UVB pre-irradiation. The results showed that the cells were not harmed in terms of viability; even more, they were encouraged to differentiate in osteoblasts and to become osteogenically active, as confirmed by the calcium ion uptake and the formation of well-mineralized, bone-like nodule structures. In addition, the enrichment of hydroxyl groups on the HT-surfaces by UVB photofunctionalization accelerated the cell differentiation process and greatly improved the osteogenesis in comparison with the nonirradiated samples. The optimal surface characteristics of the HT-anatase coatings as well as the high potentiality of the photo-induced hydrophilicity, which was reached during a relatively short pre-irradiation time (5 h) with UVB light, can be correlated with better osseointegration ability in vivo; among the samples, the superior biological behavior of the roughest and most hydrophilic HT coating makes it a good candidate for further studies and applications.